An internal combustion engine having a multi-valve cylinder head with an injector or spark plug opening near the valve openings may experience damage by cracking when placed under high pressure or high thermal loads. Damage may include cracking between the injector/plug tip and the valve seats proximate thereto. Once the damage occurs, repair options to the cylinder head are limited, where if repair is possible, the efforts are often costly and time consuming.
FIG. 1 sets forth a cylinder head 100 showing a cross section of an injector bore 120 above the valve seats in a cylinder head of an internal combustion engine. From FIG. 1, the injector body is positioned from above the top of the cylinder head, through the fuel-sealing region (as noted at the rectangular O-ring groove 145) just above 140 and the tapered portion of the injector located approximately adjacent to 150 near the combustion sealing cone 160. Further, the combustion face is set forth as 199. Cylinder heads may experience damage in certain situations by cracking. When cracking of the head occurs, often a crack may be observed near the thinner material area where the injector tip conical machining approaches the combustion face 199. Cracks which may initiate may often grow radially outward towards the valve seat bore area 170 and occasionally into the injector bore area at approximately 180.
U.S. Pat. No. 6,474,285 sets forth an approach to first drill a hole at the damaged spark plug hole using a drill bit and stopper to provide a drilled hole. The approach then taps the drilled spark plug hole to create a threaded hole having a limited thread depth, where after a steel insert is threaded into the threaded hole with the stopper guiding the insert to a required depth. The approach then seats the insert to provide a spark plug seat. The approach is limited however in that it fails to provide either structural integrity to the damaged area and does not provide for a combination of crack repair and injector sleeve functionality. The approach is further limited as it fails to provide an insert solution having either radial or axial compliance. As a result of this repair, engine performance, and economics of the approach are less than desired.
U.S. Pat. No. 6,668,784 sets forth a replacement thread insert for the threads and tapered seat of a damaged tapered seat spark plug bore without the need to create a helical insert. The replacement insert is limited in its application as it fails to provide either structural integrity to the damaged area and does not provide for a combination of crack repair and injector sleeve functionality. As before, the approach is further limited to a spark plug.
U.S. Pat. No. 4,112,906, shows a firing deck insert for an internal combustion engine which includes a boss that is threaded into the cylinder head to support the insert. The configuration of the firing deck insert in Spencer requires a certain amount of precision machining for the firing deck insert. Moreover, there is no provision in this reference of some means for sealing around the valve openings in the insert. The approach is further limited as it fails to provide an insert solution having either radial or axial compliance. As a result of this repair, engine performance, and economics of the approach are less than desired.
Various conventional sleeve and cylinder head designs possess various complexities in the cylinder head to satisfy long term cylinder head durability requirements, and these complexities sometimes involve expensive details requiring tight tolerance and process controls.
What is needed is a method for repairing a multi-valve cylinder head, having an injector or spark plug opening near the valve openings, that provides an insert with structural integrity capable of providing both a repair for the crack and injector sleeve functionality for a cylinder head casting, allowing for a large injector tip/injector bore opening in the machined head. Preferably a resulting structure would enable an insert to enter into the valve seat bores, where the space could then be used to provide axial and radial compliance. The present invention, further described below, provides and satisfies such a desire.